This invention relates generally to a surgical instrument for creating an operative space during surgery. More specifically, it relates to such an instrument which creates this space by dissecting a desired layer of tissue from remaining tissue layers.
Tissue dissection to create space at a desired surgical site has been a focus of design engineers concentrating on the development of new surgical instrumentation. An increasingly popular method to dissect tissue involves inflating a balloon between adjacent tissue layers to separate those layers and create the desired space. Surgical procedures and instruments incorporating an inflatable balloon to carry out these procedures are described in U.S. Pat. Nos. 5,309,896 and 5,269,753; and published PCT International Application Nos. WO 92/212 95 and WO 93/097 22. Alternatively, dissection can be carried out manually without the aid of an inflatable balloon.
Another recent development in connection with surgical instruments is described in U.S. Pat. Nos. 5,271,380 and 5,334,150. These patents describe trocars for the penetration of bodily tissue. Unlike a conventional trocar in which the penetration of the tissue is performed blindly, the trocars described in these patents enable the user to simultaneously visualize the penetration of tissue as the trocar is advanced through the body wall. Trocars which enable simultaneous visualization are now referred to as "optical trocars". An optical trocar consists of a rigid tubular shaft to which is attached a transparent penetrating window. An endoscope for illuminating the surgical site and transmitting images of the site to the surgeon is received in the tubular shaft and extends adjacent the transparent penetrating window.
Unfortunately, the optical trocar described in the patents above may not always be ideal for creating needed operative space by carefully dissecting adjacent layers of tissue. In addition, the balloon dissectors currently available do not provide for simultaneous visualization as the surgeon is dissecting tissue.
Recently, General Surgical Innovations ("GSI") has shown a prototype product of what it refers to as the SPACEMAKER.TM. II Surgical Balloon Dissector. This dissecting instrument consists of a rigid hollow shaft to which is attached an inflatable balloon. The endoscope is insertable through the shaft, and the brochure accompanying this developmental instrument indicates that the endoscope is capable of providing for visualization during insertion as well as during balloon dissection. Unfortunately, when the endoscope may be inserted through the hollow shaft, the lens on the tip of the endoscope may be exposed to direct tissue contact as the instrument is advanced during insertion. The direct contact between the endoscope lens with the tissue and the lack of separation between them causes a significant deterioration of the visual capabilities of the endoscope, and therefore fails to satisfactorily address the problem of providing adequate visualization during the advancement of a balloon dissector. In addition, the position of the endoscope in relation to the inflated balloon is undesirable for optimum viewing. This is so because the endoscope is not readily supportable and positionable into and through a significant portion of the inflated balloon.
In view of these deficiencies inherent in the surgical instruments described in the references above, the surgical community needs a balloon dissector which satisfactorily enables the user to visualize during insertion, and to dissect the tissue when the balloon is inflated. The surgical community also needs an instrument which includes an elongate hollow shaft for receiving an endoscope to provide visualization during surgery, but also enables the user to position and support the endoscope significantly beyond the distal end of the shaft for optimum viewing.